Wasn't it agreed on with The Queen and Parliament that Camilla has chosen to take up the title HRH The Princess Consort when Charles comes to the throne?

On the list of Facts on The Prince of Wales website it says:
"As was explained at the time of their wedding in April 2005, it is intended that The Duchess will be known as HRH The Princess Consort when The Prince of Wales accedes to The Throne."

People in the United Kingdom have the right to call themselves whatever they wish, so I'd think all she has to do to not use the title Queen is choose not to use it. I think in theory anybody could ask to be called "HRH the Princess Consort" and it would be perfectly legal.

Except that she cannot just start using a title or style that (a) doesn't exist and has to be created by The Sovereign with Letters Patent; (b) is not held by her husband, The King, and creates a morganatic marriage since she would not hold equal rank as Her Majesty The Queen.

If they really want to prepare for the future, The Queen should issue Letters Patent now creating Camilla a Princess of the UK in her own right with the style of "HRH The Princess Camilla".

At that point, she would hold her own title and style and when the time comes, Parliament could simply assent (assuming the Crown Commonwealth agrees as well) that she would continue to hold her current title and not use the rank and style of Queen Consort. Charles could then simply announce his wife would hold precedence and place next to The Sovereign.

Wasn't it agreed on with The Queen and Parliament that Camilla has chosen to take up the title HRH The Princess Consort when Charles comes to the throne?

The key word is "intended" which is not the same as "legal". When this was questioned by members of Parliament, the Lord Chancellor confirmed Camilla would hold all the titles and styles of Prince Charles upon marriage and the question of her future title was not being addressed at this time.

So, in other words, she holds equal rank now and will in the future, therefore, if the public is adamantly opposed when the time comes, it will have to be addressed by Parliament with legislation.

I really don't see Parliament passing a new act to give Camilla the title "The Princess Consort", the wording from royal aides has always been that Camilla will be "known" as The Princess Consort, to me that suggests a big difference from what she is legally entitled to be called and which title she actually uses on a day to day basis.
When he becomes King surely Charles can create any title he wants (Within reason - and this title is based on Prince Consort of the past) for his wife.
To me it is like how Camilla is know as The Duchess of Cornwall, she holds the title The Princess of Wales at present but chooses not to use it, likewise she will, IMO, be Queen legally but not use the title.

Yes, but the difference is, her husband is The Duke of Cornwall, in addition to all of his other titles, which makes Camilla automatically The Duchess of Cornwall. Using her ducal title, instead of her title as Princess of Wales, as her primary style is her choice and not an issue because she holds equal rank as HRH.

Once Charles become King, his wife is automatically HM The Queen in her own right for life. She is no longer HRH or a Princess because her husband is no longer HRH or a Prince.

When Charles is King, he will be the Duke of Lancaster, as The Queen is right now. Perhaps Camilla may use the title Duchess of Lancaster, then there would not be a need to create the title of Princess Consort.

She will, however, not be Queen in her own right, as she is still taking her titles from Prince Charles. A "Queen Regnant", like Queen Elizabeth, is a queen in her own right. Camilla will be "Queen Consort".

Except that she cannot just start using a title or style that (a) doesn't exist and has to be created by The Sovereign with Letters Patent; (b) is not held by her husband, The King, and creates a morganatic marriage since she would not hold equal rank as Her Majesty The Queen.

She can call herself just about whatever she wants so long as it's not fraudulent. There's very little in the way of "cannot" involved in what people say they are. She could wake up tomorrow calling herself the Queen of Siam if she wanted, and society at large would be free to call her that.

It's true that she might not be the Princess Consort, but people aren't required to be, for lack of a better word, truthful in their social interactions.

...I think there is zero chance any future Parliament would agree to pass legislation consenting to this, so Camilla will indeed be "HM The Queen" when her husband becomes King.

You are absolutely right if it had ever been intended to legally deny Camilla the title and style of the Queen - which I don't believe to be the case.

To me, the most logical scenario (again, if they ever do proceed with the whole Princess Consort thing) is for Camilla to be created The Princess Consort in her own right. Then, while she will legally be Her Majesty The Queen, she will be able to use the lesser of her two titles, The Princess Consort, on semi-official and/or private occasions, and The Queen on state and/or official occassions.

I do sincerely hope though that this will never take place and Camilla will be known only under the style and title she will be entitled as wife of the King - Her Majesty The Queen.

When Charles is King, he will be the Duke of Lancaster, as The Queen is right now. Perhaps Camilla may use the title Duchess of Lancaster...

That was actually the title proposed for Wallis Simpson back in 1936 if she married The King morganatically, but it was rejected by the Baldwin Government. The Sovereign cannot be a Peer as the fount of honour and it is merely a style used when in the Duchy on official business ("HM The Queen The Duke of Lancaster").

Camilla would be Queen Consort as the wife of The King but in her own right as "HM Queen Camilla" for the rest of her life.

I agree the best way to handle the issue would be to create her a Princess of the UK in her own right, but it would have to be done before her husband became King to avoid legislation. She would then have her own title and style and could choose to continue using it even though she is automatically Queen.

I highly doubt this will come to pass as it makes no sense to deny her the right to be Queen when she is entitled to share her husband's titles and styles now.

This does seem like a very awkward thing, passing special laws and LPs to change her title to Princess Consort, which would perhaps create more attention than just having her automatically become Queen when Charles becomes King. I wish they'd never published that intention, but I guess they thought it was the best choice at the time. Surely Charles, when he becomes King, can simply say he wishes his wife to have full honors as Queen Consort.

I predict it will be a non-issue. Camilla is already accepted by the public as a member of the royal family at this point and I think it would be viewed as inappropriate to deny her the right to be Queen.

Given The Queen's good health, it could be 15 years before Charles becomes King if she lives as long as her mother did.

I think the way in which she, and Prince Charles, wish her to be addressed, will be her title. I don't think it will require a special session of Parliament for it to take place, as many seem to think will be the case. If she want to be called HRH Rooty Tooty Fresh and Fruity, that is how she will be addressed, and there will be no constitutional crisis.

Consort question: While Elizabeth was Queen, there were years before Philip was made a prince of the United Kingdom where he was HRH the Duke of Edinburogh. How was he referred to as a consort during that time? Prince Albert was Prince Corsort as well, but he was a prince in his one right. Prince Philip had delinquished his prince title before marriage to Elizabeth. I'm just curious...